import java.util.Scanner;

public class Test2 {

    //
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();

       CharacterList characterList = new CharacterList();

        System.out.println(characterList.chList(s));
        sc.close();

    }


}
class CharacterList{

    static boolean[] flgs = new boolean[126];

    public static String chList(String str){


        StringBuffer stringBuffer = new StringBuffer();

        for(char ch:str.toCharArray()){

            if(!flgs[ch]){

                flgs[ch] = true;
                stringBuffer.append(ch);

            }

        }
        return stringBuffer.toString();

    }

}


